Propeller



May 30, 1939. A T 2,160,323

PROPELLER Filed June 15, 1937 Inventor 215.362/"0377 2mm 7 M 5m A iior neys Patented May 30, 1939 UNITED STATES PATENT OFFICE 1 Claim.

This invention relates to a propeller, the general object of the invention being to provide means whereby air or other fluid is forced from the pressure side to the vacuum side in such a manner as to relieve the vacuum on the vacuum or rear face of the propeller and this also eliminates the roaring sound and enables the propeller to be driven with less effort.

This invention also consists in certain other features of construction and in the combination and arrangement of several parts, to be hereinafter fully described, illustrated in the accompanying drawing and specifically pointed out in the appended claim.

In describing the invention in detail, reference will be had to the accompanying drawing Wherein like characters denote like or corresponding parts throughout the several views, and in which:

Figure 1 is a view of the front face of a pro- 80 peller constructed in accordance with this invention.

Figure 2 is a view of the rear face of the propeller.

Figure 3 is a section on the line 3-3 of Figure 2, this figure showing in dotted lines how the slot causes the air passing therethrough to pass over the vacuum face of the blade.

In this drawing the propeller is made as usual with the hub portion l and the two blades 2, each blade is tilted in the usual manner and tapers from its leading edge 3 to its trailing edge 4 and the pressure face 5 of the blade is substantially flat while the vacuum or rear face 6 is shaped as shown in Figure 3.

In carrying out my invention I form each blade with a slot 1 which passes at an angle through the blade from the face 5 to the face 6, the slot starting at a point adjacent the leading edge 3 and terminating in the vacuum face 6 at a point closer to the trailing edge than the leading edge. The slots are slightly inclined with respect to the longitudinal axis of the blade with their inner ends located closer to the leading edge than are their outer ends. Each slot is formed with a fiat sloping front wall 1 and the rear wall parallels the front wall for the major portion of its length but terminates in a rounded portion 1" where it joins the vacuum face 6 of the blade. Thus the outlet end of the slot is wider than the entrance end and this provides a free flow of air through the slot and there is no danger of the air flow being retarded which would act as a resistance to the movement of the blade through the air.

Thus, as shown in dotted lines in Figure 3,

some of the air or fluid contacting the pressure face or the blade is forced through the slot and emerges at the vacuum face and this air flows along the vacuum face so as to relieve the vacuum and eliminate the roaring noises caused by vacuum. As the air passes through the slot it strikes the flat sloping front wall 1 of the slot which 5 directs the air along the rear portion of the top face of the blade and thus relieves the vacuum that would occur there if the slot was eliminated. This flat wall of the slot must be cut at the exact angle for the particular blade on which it is 10 used as it is the angle of this wall that controls the air stream across that part of the blade where the vacuum would be created.

The slot is made inclined to the longitudinal axis of the blade for the reason that a part of the 15 blade near the hub is traveling slower than a part of the blade remote from the hub. Therefore, there would be more vacuum created at said point remote from the hub. As the help of the atmosphere is depended upon to a certain extent 20 to curve the air stream through the slot around the vacuum part of the blade it is necessary that the air escapes from the slot nearer the trailing edge at the outer end of the blade than near the hub in order to offset for the difference in the traveling speed and varying vacuum effect as the slotted part recedes from the hub.

It is thought from the foregoing description that the advantages and novel features of the invention will be readily apparent. 30

It is to be understood that changes may be made in the construction and in the combination and arrangement of the several parts, provided that such changes fall within the scope of the appended claim. 35

What is claimed is:

In a propeller of the class described, a blade of. solid construction and having a pressure face and a vacuum face and said blade having a longitudinally extending elongated slot therein, the hub end of which is farther from the trailing edge than is the tip end thereof from said edge, said slot sloping gradually from a point on the pressure face adjacent the leading edge of the blade to a point on the vacuum face closer to the trailing 5 edge than the leading edge, the sloping front wall of the slot being fiat and acting to direct the air passing through the slot along the rear portion of the vacuum face of the blade and the major part of the rear wall of the slot paralleling the 50 front wall but terminating in a curved portion which merges into the rear part of the vacuum face of the blade, the air passing'through said slot acting to relieve the vacuum on the vacuum 55 side of the blade.

TRACY B. BARNETT. 

